Erasing tool



May 11, 1948. J 2,441,441

ERASING TOOL Filed Sept. 5, 1946 6 I 'jgal.

weWZZ" atented May 11 1948 UNITED STATES PATENT OFFICE ERASING TOOL Jens A. Paasche, Chicago, Ill. Application September 5, 1946, Serial No. 694,953

5 Claims. 1

The present invention relates in general to erasing tools and, inparticular, to an erasing tool which is arranged to produce a fine. streamof air carrying. eraser abrasive which is. directed against a surface that is-to be erased.

One of the objects of the present invention is to provide a new and improved power eraser which is light in weight and-convenientto handle.

Another object.- of the; invention; is to provide an improved form of eraser which is capable of cutting lines or dots from a large area: by means of a fine jet of compressed air carrying eraser abrasive.

Still another. object of. the invention is. to. provide animproved form of power eraser which is capable of erasing very rapidly: and at. the same time is adapted to perform. delicate. erasing. opera.-

tions.

A still further objector the inventionisz, to proide an improved. eraser; of: the, type described, wherein all partssubjectedtothe streamer air carrying eraser abrasive. are especially designed to withstand. abrasive action. and are. arranged to bereplaced readily.

These and other objects of. the; invention will appear upon a. perusal of the: following specification taken in. conjunction withtheaccompanying drawing, wherein;

' Fig. 1 is an elevationalview of-the erasing tool of the present invention;

Fig. 2. is an. enlarged sectionalview of the erasing tool shown inFig; and V Fig. 3 is av sectional view; ata further enlarged scale, of a portion of, theeraser shown in Eig:,. 2 taken along the'section line 3-3 thereon.

Described briefly, the eraserof the present. in.- vention comprises a cup assembly in which powderedabrasive is placedand. whichv is provided with an. outlet terminating in-.a jet. The-cup as-, sembly includes an; inlet through which, com!- pressed air is at. times admitted. When. air is ad.- mitted to the cup assembly'it createsa fine mist of abrasivewhich.iscarried withthe air through the outlet and issues from the] jet in a fine stream traveling at a highvelocity; The cup assemblyis attached to a; handle. provided with a valve adapted to be operated by" the index finger for convenience in operation of the eraser; which is preferably held in thesame manner as a penclli Referring nowto the drawing; cup: assembly in which the abrasivemateriali ispl'aced comprises a cylindrical'powder" cup 4 having. a; cap t threaded thereon: at its upper: end and: having a conically shaped portionat its lower end which isthread'ed ona stem: 8: powder tube: l0 extends within and is threaded into the stem 3. The space between the stem 8 and the powder tub-e l0 forms. a passage. through which air is admitted to the powder cup. A cup-shaped defiector i2 is secured to the powder tube III at the point where it issues from thestem 8. The lowermostedge of the deflector I2 is spaced a short distance from the upper face of the stem- 8 to cause: air admitted to the powder cup to traverse a circuitous path in its passage therethrough, and in addition: is provided with two or more skewed slots I4 (Fig- 3-), which are preferably substantialh, tangential to" the outer diameter of powder tube III, in order to impart a whirling action to the; air admitted to the powder cup; The upper end ofthepow-der tube I'll is spaced a short distance from. the cap- 6, which has an adjusting screw: I56 threaded therein in. axial. alignment with the powder tube [0. The adjusting screw [6 is provided with: a hardened steel cone-shaped insert I'd which matches a hardened steel cylindrical insert 20. secured within; powder tube III' at the: upper end thereof. A coil spring. 22 maintains tension on adjusting screw 16 to. prevent undesired movement thereof.

The; cup assembly is supported by the stem 8 which extends from a body portion '24 of the eraser; The body portion; 24 is: provided with. a passage 16 communicating with the powder tube til at the lower end: thereof and with a hardened steel jet 28 which is: secured to the body portion 24 by means or a flanged nut 30. The body porticn 24 also includes a chamber 3'2 and a passage 34; extending f'ro'm the chamber 32 through the body-portion 24 and through: the stem 8.

A second: stem 36 extends from the body portion- 24 or the eraser. A val ve casing 33 is threaded into the stem 36- The valve casing 38 ispr0v-id'ed with: suitable threads at its lowermost. endz toperrnit an air hose to be coupled thereto. Awalve: head 41!, secured. tothe lower end of aip'lunger 42-, is biased upwardly by means of a coil spring M extending between the lower end of the plunger"; anda. hollow nut 46 which is threaded intothe: valve casing-i8 at'its lowermost: end. rod: 48; extends within athreaded shank of theivalv'er casing 3H and: fits over the end 'of the' vaalve plunger 42'; The. rod; 48- is terminate'd' at its upper end by afinger button 50, means of which the valve may be operated to admit: air: to? the. chamber 322 through. a pas sage 52 extendingthrough the body. portion 24 and the stem'. 36 fromiarr airxhose'; (not shown) is attached. to: the valve casing 38; A

3 and having a hollow shank is threaded over the upper end of the threaded shank portion of valve casing 88. The adjustment of nut 54 determines the extent to which the air valve may be opened when the finger button 58 is depressed as far as possible. A collar 56 is forced on the rod 48 to retain the rod 48 and finger button 50 within the stroke adjusting nut 54. A hollow handle 58 is threaded into the body portion 24 of the eraser to enable grasping thereof in the same manner as a pencil is grasped.

The valve head 40 is normally pressed into air-- tight engagement with the valve casing 38 to prevent entrance of air into the chamber 32.

When the finger button 58 is depressed. the ,valve head 48 is disengaged from the valve casing 38,

also be used for highlighting or shading by holding the jet 28 some distance from the working surface, producing results heretofore unobtalnable with erasers of any type.

It should now be apparent that an eraser of great utility, which is constructed in such manner as to permit delicate erasing operations to be performed in a rapid manner, has been provided. The initial cost and the cost of maintenance of the eraser are reduced to a minimum by the provision of replaceable parts of abrasive-resisting materials at the points where the greatest abrasive action occurs. A high degree of uniformity in the permitting air to flow from the air hose (not' shown) coupled to the valve casing 38, through the hollow nut t8, between the valve head 48 and valve casing 38, through a passage 68 in the valve casing and the passage 52 extending through the stem 36 and the body portion 24 of the eraser into the chamber 32. From chamber 32 the air flows through the passage 34 into the space between powder tube I8 and the stem 8, thence through the gap between the lower edge of the deflector l2 and the face of the stem 8 into the powder cup 4. As the air flows through the powder cup it picks up-particles of eraser abrasive and propels them through the powder tube [8 and the jet 28, from which the air carrying abrasive issues in a fine stream.

A portion of the air admitted to the powder cup 4 will flow through the slots [4 in the cylindrical wall of the deflector l2, creating a whirlwind as indicated by air flow lines 62. The oreation of a miniature whirlwind within the powder cup 4 causes eraser abrasive contained therein to be greatly agitated, producing a fine mist of eraser abrasive in the powder cup, and also increases the length of the path along which the air passes in its travel through the powder cup, thereby causing greater uniformity in the distrihution of abrasive particles in the air stream which issues from the eraser.

The amount of eraser abrasive contained in the air stream issuing from the eraser may be regulated by means of the adjusting screw [6 to vary the width of the gap between the adjacent ends of the adjusting screw and the powder tube. The hardened steel inserts l8 and 28 provided at the tips of adjusting screw l6 and powder tube It, respectively, preclude rapid wearing of these parts as a result of the severe abrasive action which takes place thereat due to the high velocity of the air stream in the narrow gap therebetween. The jet 28 is likewise subjected to severe abrasive action due to the high velocity of the air carrying abrasive issuing from the tipv thereof, and therefore is preferably formed of hardened steel. It will be noted that all of the parts which are subjected to severe abrasive action are arranged so as to permit ready replacement thereof,

The jet 28 is made replaceable for the additional reason of enabling differently shaped tips to be employedfor particular types of work.

It has been found that the stream of eraser abrasive which issues from the jet of the eraser permits removal or cutting of ink, paint, or the like, from a drawing or like surface in a minimum of time without injury to the surface or adjacent areas which it is not desired to erase. To effect a complete erasure, the jet may be held close to the working surface. The eraser may distribution of the eraser abrasive throughout the air stream issuing from the eraser is obtained by reason of the construction of the powder cup assembly, which requires the air to travel the full extent. thereof and furthermore causes the air to traverse a spiral path during its travel through the powder cup.

While the invention has been illustrated by the disclosure of a particular embodiment thereof, it should be apparent that various modifications may be made therein without departing from the invention in its broader aspects, and therefore it is the aim in the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. An erasing tool comprising a slender hollow body portion adapted to be held like a pencil by an operator, a fitting for connecting a source of compressed air to said body portion, a finger operated valve in said body portion for controlling the flow of air therethrough, a, container for eraser abrasive attached to said body portion and communicating with said valve, a jet at the tip of said body portion, and means forming a passage for directing air admitted to said container from said body portion to said jet, whereby particles of eraser abrasive are propelled through said jet by the air stream when said valve is opened during operation of the tool.

2. An'erasing tool comprising a container for eraser abrasive having an inlet for compressed air and having an outlet for compressed air mixed with particles of eraser abrasive, and a cupshaped deflector having skewed openings therein disposed in alignment with the inlet in said container for causing compressed air flowing therethrough to traverse a spiral path through the container and thereby promote intimate contact between the air stream and the particles of eraser abrasive in said container during operation of the tool.

3. An erasing tool comprising a cylindrical casing having an end portion provided with an axial opening, a cover closing the other end of said casing, said cover being removable to permit eraser abrasive to be placed in the enclosure, a powder tube extending co-axially through the opening'in said end portion to a point adjacent said cover, the space between the other wall of said tube and the opening forming a passage through which compressed air is admitted to the enclosure, an annular deflector encompassing said tube and disposed in the path of the air stream to cause it to traverse a circuitous path through the enclosure, and a valve member extending axially through said cover and adjustably spaced from the adjacent end of said tube to regulate the quantity. of eraser abrasive which is carried through the powder tube by the air stream during operation of the tool.

4. An erasing tool comprising a cylindrical casing having a. cone-shaped end portion provided with an axial opening, a cover closing the other end of said casing, said cover being removable to permit eraser abrasive to be placed in the enclosure, a powder tube extending co-axially through the opening in said cone-shaped portion to a point adjacent said cover, the space between the outer wall of said tube and the opening forming a passage through which compressed air is admitted to the enclosure, a, cup-shaped annular deflector encompassing said tube and disposed in the path of the air stream, said deflector having skewed openings therein to cause the air stream to traverse a spiral path through the enclosure, and a valve member extending axially through said cover and adjustably spaced from the adjacent end of said tube to regulate the quantity of eraser abrasive which is carried through the powder tube by the air stream during operation of the tool.

5. An erasing tool comprising a slender hollow body portion adapted to be grasped like a pencil by an operator, a fitting extending from said body portion for connecting a source of compressed air thereto, a finger operated valve in said body portion for controlling the flow of air therethrough, a, cylindrical casing having an end portion provided with an axial opening communicating with the interior of said body portion, a cover closing the other end of said casing, said to traverse a spiral path through the enclosure, a

valve member extending axially through said cover and adjustably spaced from the adjacent end of said tube to regulate the quantity of eraser abrasive which is carried through the powder tube by the air stream during operation of the tool, and a jet at the tip of said body portion communicating with said powder tube.

JENS A. PAASCHE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 554,299 Parker Feb. 11, 1896 1,712,804 Wytcherly May 14, 1929 1,730,195 Davis Oct. 1, 1929 2,133,149 Poncelet Oct. 11, 1938 2,305,976 McKnight Dec. 22, 1942 

